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MathieuChailloux / FragScape

A QGIS plugin to compute mesh effective size
GNU General Public License v3.0
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Coherence increases despite increasing fragmentation #6

Closed HeiKima closed 4 years ago

HeiKima commented 4 years ago

Hi, More a question than an issue. Using the CBC method it occurs in some cases that the coherence (or rather probability) is lower for less fragmented scenarios than for more fragmented. Calculating the coherence for a 0-Case scenario without any roads the result is:

nb_patches: 3 reportarea: 100000000 intersecting: 6516029,456 effective mesh size: 44663524,28 coherence: 0,010697887

in compare to the scenario with roads

nb_patches: 8 reportarea: 100000000 intersecting: 6460566,108 effective mesh size: 5801795,57 coherence: 0,011004789

How is this possible? Maybe I don't get the maths behind it? Hope you can help me out here.

Greetings HK

MathieuChailloux commented 4 years ago

Hi, Indeed this is confusing. In CBC mode, you should juste consider effective mesh size and net product. Other metrics (coherence, splitting index, splitting density and landscape division) are irrelevant in such mode.

This shall be fixed in next published version to avoid such confusion, sorry for this.

Regards, Mathieu

MathieuChailloux commented 4 years ago

Fixed in 2.0 (only 2 CBC metrics : CBC_effective_mesh_size and CBC_net_product)